The study, conducted by a panel of 302 experts from 64 countries, was the first global analysis of the fish class. It was led by the IUCN’s Shark Specialist Group.

“Previous marine studies are based on stock assessments that are taxonomically and geographically limited,” said Nick Dulvy, a researcher at Simon Fraser University in British Columbia, Canada, and co-chair of the IUCN’s Shark Specialist Group.

“Many older studies are based on North American populations, and only on the most abundant fish in the world.”

The group found that only 23 percent of this large class of fish is listed as “least concern” on the IUCN Red List of Threatened Species. Of the 1,041 known species of chondrichthyan fish, 25 are listed as critically endangered, 43 are endangered, and 113 are vulnerable to extinction. This is the worst reported status for any major vertebrate group except for amphibians.

The Big Threats

The report suggests that overfishing, habitat loss, persecution, and climate change are the major threats to the class. Even worse, it mentions that the assessments—partially based on fisheries catching data, which are notorious for underreporting fish counts—may even be “downplaying the true risk” of these threats on sharks and rays.

The species of rays and sharks with a higher risk of extinction live in the shallow waters of the Atlantic, Indian, and western-central Pacific Oceans. Shallow waters are located closer to fisheries and are prone to overfishing. Additionally, many ray species are closer to extinction than sharks are.

“Of the sharks and rays caught and reported to the United Nations, the catch has been dominated by rays for the last 40 years and we never noticed,” he said. The threat of overfishing is not a new phenomenon. Several species of rays have been going under the radar of the fisheries for years. But the new data suggests how these rays are slipping through the system.

Dulvy gave an example: Fisheries are responsible for submitting catch landing data. When two different species are categorized as one species, then one ray could be overfished while the other one increases. According to Dulvy, this miscommunication error has led to the extinction of several different species of rays.

“Retrospectively, we’re finding that species are disappearing, and it’s because we haven’t taken the time to properly identify them,” he said.

These gray reef sharks are listed as “near threatened” on the IUCN Red List. Photo by David Doubilet, National Geographic

Lessons Learned

Fortunately, the results of the study weren’t all doom and gloom. Dulvy indicated that collaboration within the scientific community, which had developed as a result of the global study, will likely pave the way for stronger conservation efforts around the world. The plan is to use this data to teach government and biodiversity agencies about the immediate threats to sharks and rays.

“It’s not paper that conserves species, it’s people. Now 300 people that understand the population status of the sharks and rays can go back to their governments and encourage action to conserve these species,” said Dulvy.

The group recommends that improved management of fisheries and trade could help promote population recovery. The entire study can be read online at eLife.

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Ocean Views brings new and experienced voices together to discuss the threats facing our ocean and to celebrate successes. We strive to raise awareness worldwide to the benefits of restoring fisheries and creating marine reserves. We inspire people to take better care of the oceans and leave a legacy of pristine seas to future generations.

The blog is hosted by Enric Sala, Explorer-in-Residence with National Geographic.

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The photograph above, by David Wrobel, SeaPics, is from the most popular ocean gallery on the National Geographic website: Deep-Sea Creatures

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